Spark-plug.



UNTED STATES PATENT OFFICE.

ALFRED `LEAIILDEIEI; RIGGS, OF PITTSBURGH, PENNSYLVANIA, .ASSIGNOR TO VISIBLE SPARK PLUG COMPANY, A CORPORATION 0F DELAWARE,

SPARK-PLUG.

Speecation of Letters Patent.

Patented Mar. 4, 1919.

Application tiled January 23, 1917. Serial No. 143,973. Renewed July 31, 1918. Serial No. 247,672.

and useful Improvements in Spark-Plugs, of which the following is a speciiication.

This invention relates to spark plugs. lts object is to .providea spark plug in which provision is made` for ascertaining at a glance'whcther or not the ignition circuit or current is flowing across the gap between the power and ground electrodes, or is being short circuited in any of the usual ways. To this end the invent-ion comprises a spark plugin which a portion of one of the electrodes, preferably thepower electrode, is exposed so as to be visible at all times while the engine is in operation, so that a person at a glance can see whether the eurren'tis bridging the gap between the electrodes, whereby in a multiple cylinder engine a short circuitor failure of the current to bridge the gap of any particular plug is easily located, rendering it 'unnecessary to disturb any of the plugs other than the one which is at fault.

A'further object of the invention is to provide simple` and reliable means for obtaining access tothe exposed portion of the power electrode and the terminal associated therewith, said parts forming an auxiliary or pilot gap across which the current must jump before reaching the gap -forming points at the inner end of the plug.

With the above and other objects inv View,

theinvention consists in the novel construction, combination and arrangement of parts hereinafter `described and claimed.

In the accompanying drawings, Figure l 'is a view partly in side elevation and partly in diametrioal section of a spark plug enibodying the'invention; Fig. 2 is a detail perspective view of thesleeve or cap; Fig. 3 is a similar view of the coupling or clamping band g Fig. 4 is a detailperspective View of another 'form of sleeve or cap; Fig. 5 is a similar View? of the clamping band used .in conjunctionwith the cap illustrated in Fig. 4; Fig. -6 isla detail perspective view of the ring forming the auxiliary spark terminal; Fig. 7 Ais a fragmentary section similar to the upper portion of Fig. 1 showing 7moditied forms of cap, clamping band and ring terminal; Fig. 8 is a detail perspective View vof the clamping band used in Fig. 7 5 Fig. 9 is. a fragmentary sectional view similar to F ig. 'i' showing another modification in the sleeve or cap; and Fig. l0 is a similar view showing a modification in the forni of th'e ring terminal.

The present invention is an improvement on the spark plug shown in my Patent No. 1,241,012, issued Nov. 20, 1917.

The plug, as illustrated iii Fig. l, comprises the usual metal body or shell Al having the reduced and threaded portion'Q by which the plug is screwedA into a threaded hole in the engine cylinder, theclamping nut 3 which serves to tightly secure in the body or shell l, the' insulating core 4 o f porcelain or raw hide and which is provided with the central power electrode 5, and a plurality of ground electrodes 6 which protrude from the body or shell `1.

ln carrying out `this invention the end portion of the insulating core 4, beyond the shell l and the clamping nut 3, is formed with an annular recess or groove 7, and surrounding theend portion of the core 4 is a metal ferrule, sleeve or cap 8 which is of cylindrical form and provided at diametrically opposite points with outwardly projecting lips,.tenons or projections 9. Sur- 13 to receive the projections or lips 9 of the cap 8, and is further provided along the inner or bottom edge thereof with inwardly extendinglips or projections 14 adapted to enter the groove or annular 'recess 7 in the core 4, so that said band 10 serves to firmly secure the cap 8 to the exposed end portion of the core.

Within thev cap S and resting against the end of the'core 4 is a spark terminal in the forni of a feed ring 15, the inner wall or bore of which is in the shape of an hour glass, that is, formed with. reversely beveled surfaces 1G and 17 forming an annular edge or vertex 18, which encircles the exposed extremity of the electrode 5 as shown in Fig. 1. Arranged beyond the ring 15 is a transparent panel 19, usually of glass, which is confined .between packing rings 20 and 21 `of some soft material which will'prevent fracture ofthe glass panel 19. The outer endv of the cap 8 is deiected or spun in-v wardly to form' an annular retaining Aflange 22 substantiallyA semicircular 1n cross section.

The feed. ring 15, auna-raad in daan in,

Fig. 6, is split or divided diagonally as indicated at 25 so that it is rendered self ex-f panding in 4order to maintain a tight electrical contact with the inner wall of the cap 8. l

.Thefeed' wire notfshown)l of the circuit may be connected to the clamping band 10 by means vof the boltv or screwy 12 or in any otherpway desired. By reason of the fact that the band 10, the cap 8 and the ring 15 are "of metal or conduct-ing material, the current is conducted to the ring 15 and jumps therefrom lto the exposed end of the electrode 5, then passes through the lengthv of said electrode andjumps 'to the ground electrode 6 and is grounded in the usual way to the body fofl the engine.

, v,Instead of forming the cap 8 andthe clanipin band 10 in the manner hereinabove described, they may be formed as shown in Figs. 4 and 5, in which the cap 8aL is -shown as formed at diametrically opposite points with slots or. circumferentially elongated holes 23, while the clamping band 10a is formed along the inner edge thereof with inwardly. extending lips or projections 24,1

- tol engage and interlock with the threads or corrugations 26, and is also 4*provided adjant' to its inner or lower edge with inwardly extending lips or projections 28 which enter the groove'or-annular recess 7 of the core 4f. In Fig. 7 the terminal ring,

' :indie ed at 15', is shown as pressed out of vet -metal and substantially V-shaped in cross section. Its function and operation, is identical with that'of the rlng inetner form of feed ring is shown in l? 10, the same being spun or pressed out of sheet metal to comprise a hollow cylindrical body or wall 30, a recurved annular portion 31, and a circular flange 32, the opening in which is of greater diameter than the external diameter of the electrode 5 so that the current may jump from the ring to said electrode electrode.

In lieu of a ring terminal as hereinabove described, an L-shaped spark terminal 29l at any point around'thel may be brazed .or otherwise fastened to the i inner surface of the cap 8c, as shown in Fig. 9, the extremity of said terminal being located at such distance from the adjacent exposed extremity of the electrode 5 as to provide for the necessary gap across lwhich the spark mustV jump.

' Under any of the forms hereinabove described and illustrated in the drawings, the current, in orderto reach the electrode 5, must jump across the gap between the terminal and the electrode 5. The chamber `in which this spark takes place is inclosed and protected by the transparent panel hereinabove described which is located directly in the end of the. spark plug. The attendant may thus observe at a glance whether or not the current is reaching the electrode 5 and therefore reaching the sparking points formed by the power and ground electrodes at the inner end of the plug. This is especially valuable in multiple cylinder engines.'

as the attendant may quickly ascertain which plug or plugs4 are failing to perform,

their function. The arrangement described also operates to intensify the spark delivered within thecombustion chamber of the cylinder by reason of the fact that the current is forced tol bridge two gaps instead of the usual single gap. By loosening o r removing the clamping member 12, the clampin band and the cap 8 may be quickly detac ed so as to give access to the ring terminal and the adjacent end of the power electrode forl cleaning on repairpurposes.

The cap or sleeve 8 with the contained and attached elements forms an attachment which canbe applied to any type of vspark plug having an insulating core with an axial electrode, and in case of breakage of the core said attachment can be removed and applied to a new plu The auxiliary or pllot spark gap is entlrely inclosed so that 1t cannot short-circuit and be rendered vin` operative by the entrance of moisture or dirt. The upper surface ofthe glass 18 is. exposed andreadily accessible for cleaning so that the spark is at all -times visible.

The attachment is very compact and pro-- jects above the top of the insulating-core only a short distance, and therefore avoids unnecessary projecting parts` which would be liable to injury when working around the engine, or which would, be broken yin case the plug is accidentally dropped.

I claim 1. In a spark plug, asplit feed ring with Legame current conducting cap serving to hold said feed icing in fixed relation to said electrode.3 means for anchoring said cap to the core ie plug, said means consisting of a ng bend encircling Said cap, said cap Iand band having one a projection and the otheid an opening to receive said projection, to prevent movement of the band and een.

3. ln a spark plug, in combination with an insulating core and1 elect-rode ei:tendingtherethrough and projecting loejjvond the end theieoil of an auxiliaryv spari: attachment comprising a metal sleeve or errule Fitting over the end of said core'and open at its outer end, a spark terminal in said sleeve or ferrule in conducting relation thereto and in sparking relation to the end of Said electrode, a transparent member in said sleeve or ierrule outside of said spark terminal and closing' the open end of said 'Sleeveor :terrule., and means for securing; Said Sleeve or ierrule to saidv core,y said means consisting ot' a clamping` ringencircling said sleeve oi ferrule und having a. separa-hie ann inter' locking' w'znncction therewith. and limiti@ means; to engage said core.

le ln a parli plug, in combina-tion u ,on insulatiufj core and an electrode extending 'therethrough and projecting l" ond'the end ther-coi' of an uuxili .ry ep attachment connarisingj a metal sleeve or rule. iitrting ove? the end of said core and open at. its outer end, a spari; terminal in said sleeve or ierrule iu conducting relation thereto and in :marking relation. to the cmi. ci said electrece.l a transparent member 'n 4:aid sleeve ci j riulc outsy ic ot said spari einiinal and closing the open end et' said sleeve or 'terrulc. and menne for Sec-uric iid sleeve or liu-rule to Said core, l me coi'isieting a. Split clamping i' 'f said rule and opening to receive Said projection to interlock the same.

5. ln a spark plug, in combination with an insulating' core provided near its outer end with a recess, and an electrode extending; through said core and projecting beyond the end thereof, of an auxiliary Spark attachment comjgirising a metal sleeve or 'l`er rule litting over 'the end of Said core and open at its outer end, a clamping` ring; eurroundingsaid .sleeve or ferruleand provided with inturned portions engaging the recess in the core and serving to secure the sleeve or feriule to the core, a spark terminal in Said sleeve in. conducting relation thereto and in sparking relation to the end of eaiff. i ode, and a transparent member in said ve outside ont seid spark ter-miami and ciosin the open end of said sleeve.

6. 'ln i spari-z plug, in combination. with.

c ing core provided neer its outer end ec-ees, and an electi-*ode extendng; minnen s Le. core and projecting' beyond tite @nel then i, ci en auxiliary spa rift tf-,wl-nneiit coingrieing a metal sleeve or fer- 'rule t of. r tlie end ci said core and open at its outei endj a. Spark terminal in in sparking' relation to the end of 'said trede, a transparentinomber in said l outside ot said spank terminal and ch the open end of Said sleeve.l and a split clamping ring; surrounding said :sleeve or :terrule and having interlocking; t thei'eifsith and provided with menue entering the recess in the core and serving* secure me sleeve to the core.

'.1 l'n'a spark pluga in combination with un. ins:ulatingcore provided near its; outer end with a recess and an electrode ex t ending through said core and projecting; hej/ond the cnil thereof, of an auxiliary spark attachvmont comprising a metal Sleeve or errule fling over the end; of said corel and open :it its outer endz a. spark terminal in said cete in conducting; relation thereto and in sparking relation to the end oil? Isaid electrode. a transparent member in said sleeve outside of said spark terminal and closing the ope-,i end of said sleeve, and `a split clamping ring;- surrounding' said Sleeve or ieri'ule and pimf'ided with means?. entering tlierecess in the core, saidslee've and ring a one a, project-ion and the other an openingto receive said projectionl` in 'iieetinnmy whereof I atlix my signature.

MQFRED LEANDER R'IGGS.

age ment 

